What is LTP Food? Understanding a Complex Food Allergy

November 20, 2025 •

4 min read

While most food allergies are caused by a specific protein, LTP food allergy, or Lipid Transfer Protein syndrome, is triggered by a pan-allergen found in a wide variety of plant foods. This makes it particularly challenging to manage, as reactions can be severe and unpredictable.

Quick Summary

LTP food allergy is an immune system reaction to lipid transfer proteins found in many plants, not just one food type. The symptoms can range from mild to life-threatening, and reactions are often influenced by other factors such as exercise or alcohol.

Key Points

Heat-Stable Allergen: LTPs are resistant to heat and digestion, meaning people with this allergy can react to both raw and cooked plant foods.
Wide Range of Triggers: LTPs are pan-allergens found in a broad array of plant-based foods, including fruits, vegetables, nuts, and grains.
Co-Factors Increase Risk: Reactions can be triggered or worsened by co-factors like exercise, alcohol, NSAIDs, and stress, even with foods that were previously tolerated.
Distinct from PFS: Unlike Pollen Food Syndrome (PFS), LTP allergy often causes systemic and severe reactions, rather than just mild oral symptoms.
Diagnosis is Complex: Diagnosing LTP allergy requires a detailed clinical history, specific allergen testing (like Pru p 3), and careful consideration of co-factors.
Emergency Management is Crucial: Due to the risk of anaphylaxis, patients with LTP allergy should carry emergency medication, including adrenaline auto-injectors.

What are Lipid Transfer Proteins (LTPs)?

Lipid transfer proteins (LTPs) are a family of small, stable proteins found in most plants, including fruits, vegetables, grains, nuts, and seeds. In plants, their primary function is to protect against pathogens like fungi and bacteria. Their robust structure, stabilized by disulfide bonds, makes them resistant to heat and digestion, unlike some other common food allergens. This stability is why LTPs can cause systemic and severe reactions even after being cooked, processed, or fermented.

The LTP Syndrome Explained

The LTP syndrome is the clinical allergy that results from sensitization to these proteins. While historically most common in Mediterranean countries, it is now being diagnosed worldwide. Sensitization typically occurs through the oral route, but can also happen via inhalation of pollen or skin contact. A key feature of LTP syndrome is that individuals can react to a broad range of botanically unrelated foods due to the cross-reactivity of LTPs from different plant species. The clinical manifestation is highly variable and often unpredictable, ranging from mild oral symptoms to severe, life-threatening anaphylaxis.

Common LTP Food Triggers and Sources

Because LTPs are pan-allergens, they are present across many food groups. The level of LTP is often higher in the peel and seeds of fruits and vegetables.

Fruits: Peaches (Pru p 3 is a prominent LTP), apples, grapes (and wine), stone fruits (apricots, plums, cherries), citrus fruits.
Nuts and Seeds: Walnuts, hazelnuts, almonds, peanuts, sesame seeds, sunflower seeds.
Vegetables: Lettuce, tomatoes, green beans, cabbage, asparagus.
Grains and Cereals: Wheat (often linked to food-dependent exercise-induced anaphylaxis), barley, corn, rice, spelt.
Processed Foods: As LTPs are heat-stable, they are not destroyed during cooking. This means processed products like tomato paste, pizza sauce, canned peaches, dried fruits, juices, and wine can all trigger a reaction.

The Role of Co-Factors in LTP Allergy

A particularly confusing and dangerous aspect of LTP allergy is the influence of co-factors, which can trigger or worsen a reaction. Without these, a person might tolerate the food, making diagnosis and management difficult. Common co-factors include:

Exercise: Physical activity can increase the absorption of food allergens from the gut, leading to a severe reaction like food-dependent exercise-induced anaphylaxis (FDEIA).
Alcohol: Ethanol can increase intestinal permeability and enhance allergen absorption.
Non-steroidal anti-inflammatory drugs (NSAIDs): Medications like ibuprofen can also increase gut permeability and lower the threshold for a reaction.
Other factors: Acute infections, stress, sleep deprivation, and menstruation have also been implicated.

Distinguishing LTP Allergy from Pollen Food Syndrome (PFS)

LTP allergy is distinct from PFS, also known as oral allergy syndrome. They differ significantly in allergen stability and reaction severity.


Feature	LTP Allergy	Pollen Food Syndrome (PFS)
Allergen Stability	Very stable, resistant to heat and digestion.	Labile, broken down by heat and stomach acid.
Food Triggers	Wide range of fruits, vegetables, nuts, seeds, and grains. React to both raw and cooked food.	Often related to specific pollen types (e.g., birch pollen). Reactions primarily to raw fruits and vegetables.
Reaction Severity	Can cause systemic and severe reactions, including anaphylaxis.	Typically mild and localized symptoms in the mouth and throat (Oral Allergy Syndrome).
Influence of Co-factors	Reactions are often influenced by co-factors like exercise and alcohol.	Co-factors generally do not play a role.
Geographic Prevalence	Higher prevalence in Mediterranean regions, but now global.	Common in Northern and Central Europe where birch pollen is prevalent.

Diagnosis and Management of LTP Food Allergy

Diagnosing LTP allergy requires a comprehensive approach, as standard skin or blood tests can sometimes be misleading. A thorough clinical history that includes details about symptoms, food triggers (including processed foods), and co-factors is vital. Testing for specific LTP allergens, such as Pru p 3 (from peach), is often recommended, especially in patients with severe reactions. Your allergy specialist may also perform skin prick tests with fresh foods, particularly peach peel, where the LTP content is higher. Oral food challenges under medical supervision may be necessary to confirm triggers.

Management focuses on avoidance of identified trigger foods in all forms—raw, cooked, dried, or concentrated. Patients should also manage co-factors, such as exercising at a different time from eating or avoiding NSAIDs. For those at risk of severe reactions, carrying an adrenaline auto-injector is essential. Working with a specialized allergist and dietitian is crucial for creating a personalized plan that balances safety with nutritional needs, avoiding unnecessary food restrictions. Research into LTP immunotherapy is ongoing and shows promising results in some populations.

The Unpredictable Nature of LTP Syndrome

The unpredictable nature of LTP syndrome is one of its most challenging aspects. Reactions can vary in severity and a food previously tolerated may cause a reaction on another occasion due to different factors, including the ripeness of the fruit, specific pollen exposure, or the presence of co-factors. This highlights the importance of patient education and ongoing support to manage anxiety and ensure a safe and varied diet. It is also a reminder that testing positive for an LTP allergen does not automatically mean a clinical allergy exists, as asymptomatic sensitization is possible. The diagnosis relies heavily on a correlation with a patient's reported symptoms.

Conclusion

In conclusion, understanding what is LTP food involves recognizing it as a severe, often systemic allergy to a stable protein found across many different plant species. Distinct from other allergies like PFS, LTP allergy can be triggered by both raw and processed foods and is often potentiated by co-factors like exercise or alcohol. Accurate diagnosis relies on a detailed clinical history supported by specific allergen testing. Effective management requires a personalized plan focusing on avoiding confirmed triggers, managing co-factors, and carrying emergency medication. As research continues, new treatment options like immunotherapy may become more widely available, offering hope for those living with this complex condition. For further information and support, consider visiting the Allergy UK website.

Frequently Asked Questions

LTP stands for Lipid Transfer Protein, a stable protein found in many plant foods that can cause a food allergy known as LTP syndrome.

No, because LTPs are heat-stable and resistant to digestion, they are not destroyed by cooking. Individuals with LTP allergy can react to cooked, processed, or raw foods containing the allergen.

Common LTP food triggers include peaches, apples, grapes, tree nuts (like walnuts and hazelnuts), peanuts, lettuce, and tomatoes. The allergen is often concentrated in the peel and seeds.

Co-factors, such as exercise, alcohol, and NSAIDs, can increase the risk and severity of an allergic reaction. They can lower the allergen threshold, meaning a food that is normally tolerated might trigger a reaction when combined with a co-factor.

OAS is a milder, localized reaction to fragile allergens typically affecting the mouth. LTP allergy involves stable allergens and can cause severe, systemic, and unpredictable reactions, including anaphylaxis.

Currently, there is no cure. The primary management is strict avoidance of identified trigger foods. However, research into specific immunotherapy for LTP allergy is ongoing.

No, dietary management should be individualized based on which specific foods trigger reactions. Avoiding only confirmed trigger foods prevents unnecessary dietary restrictions and nutritional deficiencies. A dietitian's guidance is recommended.

Pru p 3 is the name for the specific lipid transfer protein found in peaches. It is considered a prototypic marker for LTP-mediated allergies, particularly in Mediterranean areas.

The higher prevalence in Southern Europe, particularly the Mediterranean basin, is linked to higher exposure to specific pollens (like mugwort and plane tree) and a diet rich in fresh and processed fruits and vegetables.